Ribofuranosyl Purine Compounds, Methods for Preparing the Same and Use Thereof

ABSTRACT

The present invention relates to the compounds of the formulae (I) and (I-1) and the process for preparing the same, uses of the compounds for the treatment of diseases associated with platelet aggregation and in the manufacture of a medicament for the treatment of diseases associated with platelet aggregation, and relates to a pharmaceutical composition and a pharmaceutical formulation containing the compounds, wherein the definitions of R 1 , R 2 , R 3  and R 2a  in the formulae are the same as those in the description.

TECHNICAL FIELD

The present invention relates to ribofuranosyl purine compounds, methodsfor preparing the same and use thereof in the manufacture of amedicament for the treatment of diseases associated with plateletaggregation. More specifically, the present invention relates tocompounds having 9-β-D-ribofuranosyl purine as the parent structure, andcomprising a substituted amino group at 6-position and a substitutedhydrosulfuryl at 2-position, and relates to methods for preparing thesame and use thereof for the treatment of diseases associated withplatelet aggregation and in the manufacture of a medicament for thetreatment of diseases associated with platelet aggregation, and relatesto pharmaceutical compositions and formulations comprising saidcompounds.

BACKGROUND ART

Due to the biological importance of purine and the pharmacologists'studies on purine antineoplastic and antiviral medicines, purinechemistry develops rapidly. The research shows that purine compoundshave important biological activities such as anti-viral, anti-cancer,blood pressure decreasing activities. The compounds prepared by usingpurine derivatives as the intermediates have special efficacy oncancers, AIDS, thrombosis and the like. The medicines such as from theearliest acyclovir to the lately developed ganciclovir, valganciclovir,abacavir, fludarabine and the like are widely and clinically applied(Bioorg. Med. Chem. Lett. 2009, 19, 242-246 and Synthesis 2008, 20,3253-3260). In WO2004/058791A2, it is disclosed that 6-(substituted)benzylamino adenosine derivatives are thought to have anticancer,mitotic, immunosuppressive and antisenescent properties. InWO2010/130233A1, it is disclosed that2-substituted-6-(substituted)benzylamino purine riboside derivatives arethought to have antiapoptotic, anti-inflammatory and differentiationactivities.

Anthony H. Ingall et al. disclosed in 1994 (WO 94/18216)N-alkyl-2-substituted ATP analogues having the following formula, andmethods for preparing the same,

wherein R¹ and R² independently represent H or halogen; R³ and R⁴independently represent phenyl or C₁₋₆ alkyl optionally substituted byone or more substitute(s) selected from the group consisting of OR⁵,C₁₋₆ alkylthio, NR⁶R⁷, phenyl, COOR⁸ and halogen; R⁵, R⁶, R⁷ and R⁸independently represent H or C₁₋₆ alkyl; and X represents the acidicmoiety. Such PCT application further provides the representative data ofthe in vitro anti-platelet aggregation activity test of the compounds,in which the tests were carried out by using human platelet treated withwater. Anthony H. Ingall et al. further disclosed in 1999 a process forpreparing 2-alkylthio-6-(alkyl)amino-5′-substituted-9-β-D-ribofuranosylpurine compounds (AR-C compounds) having the following formula

and the results of the activity measurement of ADP-induced plateletaggregation resistance carried out by using human platelet treated withwater. The results show the above compounds have the activity ofADP-induced human platelet aggregation resistance (J. Med. Chem. 1999,42, 213-220). The AR-C compound—Canrgelor is thought to have theadvantages of high activity, fast effect, short half-life,reversibility, direct inhibition of platelet activation and the like(Eur. Heart. J. Suppl. 2008, 10, 133-137 and Recent Patents onCardiovascular Drug Discovery, 2008, 3, 194-200), and has the prospectof being developed into a new class of antithrombotics medicines. Thusstudies on the activity of anti-platelet aggregation of such5′-substituted-9-β-D-ribofuranosyl purine compounds have become one ofhotspots in the field of drug research.

However, the AR-C compounds have a complex structure, a longer synthesisroutes, and a very tedious post-treatment process, in particular abiochemical reagent is required for introducing a substitutedtriphosphoric acid side chain into the 5′-position, and the saidcompounds have a bad oral availability. Thus there is an urgent need todevelop a candidate medicine for anti-platelet aggregation having asimple structure, easy to synthesize, a better therapeutic effect and alower side effect.

During the studies on the platelet aggregation inhibitors, the inventorof the present invention discovered a series of novel 2-substitutedhydrosulfuryl-6-substituted amino-9-β-D-ribofuranosyl purine compoundshaving notable activity of anti-platelet aggregation and a simplestructure, and measured the in vitro anti-platelet aggregation activityof the compounds, so as to achieve the present invention.

Contents of the invention

One object of the present invention is to provide a compound of thefollowing formula (I) having the activity of anti-platelet aggregation,or a pharmaceutically acceptable salt thereof, as well as the usesthereof as platelet aggregation inhibitors or in the manufacture of amedicament for the treatment or prevention of diseases associated withplatelet aggregation:

wherein:

R₁ represents an unsubstituted or R₄-substituted C₁-C₈ hydrocarbyl, oran unsubstituted or R₅-substituted 5- to 6-membered cyclic group;

R₂ represents an unsubstituted or R₅-substituted C₃-C₈ saturated orunsaturated aliphatic hydrocarbyl, an unsubstituted or R₅-substitutedC₃-C₈ alicyclic group, an unsubstituted or R₆-substituted C₆-C₁₀aryl-C₁-C₄ alkyl, an unsubstituted or R₆-substituted 5- to 10-memberedheterocyclyl-C₁-C₄ alkyl, or an unsubstituted or R₆-substituted 5- to10-membered heteroaryl-C₁-C₄ alkyl;

R₃ represents H or R₂;

R₄ represents halogen, C₁-C₄ alkyl, C₁-C₄ alkoxyl, halogenated C₁-C₄alkyl, halogenated C₁-C₄ alkoxyl, hydroxyl, hydroxyl C₁-C₄ alkyl,carboxyl, nitro, cyano, C₁-C₄ alkylthio, or C₁-C₄ alkyl-CO—;

R₅ represents C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl, hydroxyl C₁-C₄alkyl, carboxyl, nitro, cyano, C₁-C₄ alkylthio or C₁-C₄ alkyl-CO—; and

R₆ represents halogen, C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl, hydroxylC₁-C₄ alkyl, carboxyl, nitro, cyano, C₁-C₄ alkylthio, or C₁-C₄alkyl-CO—.

Another object of the present invention is to provide a novel compoundof the formula (I) having the structure of the following formula (I-1),or a pharmaceutically acceptable salt thereof:

wherein

R₁ represents an unsubstituted or R₄-substituted C₁-C₈ hydrocarbyl, oran unsubstituted or R₅-substituted 5- to 6-membered cyclic group;

R_(2a) represents an unsubstituted or R₅-substituted C₃-C₈ saturated orunsaturated aliphatic hydrocarbyl, an unsubstituted or R₅-substitutedC₃-C₈ alicyclic group, an unsubstituted or R₆-substituted C₆-C₁₀aryl-C₂-C₄ alkyl, an unsubstituted or R₆-substituted 5- to 10-memberedheterocyclyl-C₁-C₄ alkyl, or an unsubstituted or R₆-substituted 5- to10-membered heteroaryl-C₁-C₄ alkyl;

R₃ represents H or R_(2a);

R₄ represents halogen, C₁-C₄ alkyl, C₁-C₄ alkoxyl, halogenated C₁-C₄alkyl, halogenated C₁-C₄ alkoxyl, hydroxyl, hydroxyl C₁-C₄ alkyl,carboxyl, nitro, cyano, C₁-C₄ alkylthio, or C₁-C₄ alkyl-CO—;

R₅ represents C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl, hydroxyl C₁-C₄alkyl, carboxyl, nitro, cyano, C₁-C₄ alkylthio or C₁-C₄ alkyl-CO—; and

R₆ represents halogen, C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl, hydroxylC₁-C₄ alkyl, carboxyl, nitro, cyano, alkylthio, or C₁-C₄ alkyl-CO—;

provided that

when R₁ is —CH₃ and R₃ is H, R_(2a) is not cyclobutyl, cyclopentyl,cyclohexyl, cycloheptyl, decalinyl, 3-methyl-2-pentenyl,2-methyl-3-hydroxyl-1-propenyl, 3-methyl-4-hydroxyl-1-butenyl,furfurylmethylene, 3-methyl-1-butenyl, 3-methyl-2-butenyl,3-methylbutyl, 3-methyl-4-hydroxylbutyl, 3-methyl-4-hydroxyl-2-butenylor 3-methyl-4-hydroxyl-3-butenyl; and

when R₁ is propyl, R_(2a) is not cyclopentyl, isopropyl, n-propyl orn-butyl.

Another object of the present invention is to provide a process forpreparing the compound of the formula (I) (including the compound of theformula (I-1) (when R₂=R_(2a) in the formula (I))), comprising usingguanosine 1 as the starting material, firstly conducting theconventional esterification protection of three hydroxyl groups on theribose ring of guanosine with anhydride or acyl halide, for example,acyl chloride, then halogenating the isomerized hydroxyl group at6-position (using the conventional halogenating reagent, such asphosphorus oxyhalide POX₃)) to obtain2-amino-6-halogenated-9-(2′,3′,5′-tri-O-acetyl-(3-D-ribofuranosyl)purine 3, then diazotizing the amino at 2-position of 3 under theanhydrous condition (with the conventional diazotization reagents, suchas isoamyl nitrite and the like), and then reacting with disulfide toobtain the corresponding2-alkylthio-6-halogenated-9-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosyl)purine 4, and eventually conducting the nucleophilic substitutionreaction with amine under the action of alkaline, and removing theprotecting group by the catalysis with organic bases, e.g. alkali metalalkoxides such as sodium, potassium methoxide, sodium ethoxide orpotassium ethoxide, to obtain the final product 2-substitutedhydrosulfuryl-6-substituted amino-9-β-D-ribofuranosyl purine compound ofthe formula (I) or (I-1) (when R₂=R_(2a) in the formula (I)). Suchsynthetic process has a simple operation, less reaction steps and arelatively higher yield. The synthetic route is shown as follows:

wherein R is acyl; X is halogen; R₁, R₂, R_(2a) and R₃ are as defined inthe compound of the above formula (I) or (I-1).

Another object of the present invention is to provide a pharmaceuticalcomposition and formulation comprising the compound of the formula (I)(including the compound of the formula (I-1) (when R₂=R_(2a) in theformula (I))) or a pharmaceutically acceptable salt thereof.

Another object of the present invention is to provide the use of thecompound of the formula (I) (including the compound of the formula (I-1)(when R₂=R_(2a) in the formula (I))) or a pharmaceutically acceptablesalt thereof in the manufacture of a medicament for the treatment orprevention of diseases associated with platelet aggregation.

Another object of the present invention is to provide a method for thetreatment or prevention of diseases associated with plateletaggregation, including administering an effective amount for thetreatment or prevention of the compound of the formula (I) (includingthe compound of the formula (I-1) (when R₂=R_(2a) in the formula (I)))or a pharmaceutically acceptable salt thereof to a mammal who needs it.

In the present invention, the term “C₁-C₈ hydrocarbyl” represents alinear or branched, saturated or unsaturated hydrocarbyl having 1 to 8carbon atoms, comprising C₁-C₈ linear or branched alkyl, C₁-C₈ linear orbranched alkenyl and C₁-C₈ linear or branched alkynyl, e.g. methyl,ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-amyl,isoamyl, neopentyl, n-hexyl, 2-methylpentyl, 3-methylpentyl,2,3-dimethylbutyl, 2-methylhexyl, 3-methylhexyl, 2,3-dimethylpentyl,2,2,3-trimethylbutyl, 2,3,3-trimethylbutyl, n-heptyl, 2-methylheptyl,3-methylheptyl, 4-methylheptyl, 3-ethylhexyl, 2,3-dimethylhexyl,2,4-dimethylhexyl, 2,5-dimethylhexyl, n-octyl, allyl, 2-butenyl,2-pentenyl, 2-hexenyl, 3-hexenyl, 2-heptenyl, 3-heptenyl, 2-octenyl,3-octenyl, 4-octenyl, propargyl, 2-butynyl, 2-pentynyl, 2-hexynyl,3-hexynyl, 2-heptynyl, 3-heptynyl, 2-octynyl, 3-octynyl, 4-octynyl andthe like, wherein C₁-C₆ hydrocarbyl is preferred.

The term “5- to 6-membered cyclic group” represents 5- to 6-membered,saturated or unsaturated alicyclic non-aromatic carbon ring group or 5-to 6-membered, saturated or unsaturated heterocyclyls, wherein saidheterocyclyls comprise heteroatoms selected from the group consisting ofN, O and S; 6-membered cyclic group is particularly preferred. Saidcyclic group includes, but is not limited to, e.g. cyclopentyl,cyclohexyl, cyclopentenyl, cyclohexenyl, pyrrolidinyl, imidazolidinyl,pyrazolidinyl tetrahydrofuryl, tetrahydrothiophenyl, tetrahydropyranyl,oxazolidinyl, pyrrolyl, dihydropyrrolyl, imidazolyl, dihydroimidazolyl,pyrazolyl, dihydropyrazolyl, pyridyl, pyridazinyl, pyrimidinyl,pyrazinyl, furyl, dihydrofuryl, thienyl, dihydrothienyl, pyranyl,dihydropyranyl, oxazolyl, dihydrooxazolyl, isoxazolyl,dihydroisoxazolyl, thiazolyl, dihydrothiazolyl, isothiazolyl and thelike.

In the present invention, the term “C₃-C₈ saturated or unsaturatedaliphatic hydrocarbyl group” represents a linear or branched, saturatedor unsaturated hydrocarbyl having 3 to 8 carbon atoms, including C₃-C₈linear or branched alkyl group, C₃-C₈ linear or branched alkenyl andC₃-C₈ linear or branched alkynyl. Said hydrocarbyl group includes, butis not limited to, e.g. propyl, isopropyl, n-butyl, isobutyl,tert-butyl, n-amyl, isoamyl, neopentyl, n-hexyl, 2-methylpentyl,3-methylpentyl, 2,3-dimethylbutyl, 2-methylhexyl, 3-methylhexyl,2,3-dimethyl pentyl, 2,2,3-trimethylbutyl, 2,3,3-trimethylbutyl,n-heptyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 3-ethylhexyl,2,3-dimethylhexyl, 2,4-dimethylhexyl, 2,5-dimethylhexyl, n-octyl, allyl,isopropenyl, 2-butenyl, 2-pentenyl, 2-hexenyl, 3-hexenyl, 2-heptenyl,3-heptenyl, 2-octenyl, 3-octenyl, 4-octenyl, propargyl, 2-butynyl,2-pentynyl, 2-hexynyl, 3-hexynyl, 2-heptynyl, 3-heptynyl, 2-octynyl,3-octynyl, 4-octynyl and the like.

In the present invention, the term “C₃-C₈ alicyclic group” represents 3-to 8-membered saturated or unsaturated alicyclic carbon ring group, andthe said group includes, but is not limited to, e.g. cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl,cyclopentenyl, cyclohexenyl and the like.

In the present invention, the term “C₆-C₁₀ aryl” represents 6- to10-membered, aromatic, monocyclic or bicyclic carbon ring group, whereinone ring of the bicyclic carbon ring group may be hydrogenated,includes, e.g. phenyl, naphthyl, dihydronaphthyl, tetrahydronaphthyl andthe like.

Said “C₆-C₁₀ aryl-C₁-C₄ alkyl” includes, but is not limited to, e.g.benzyl, phenylethyl, phenylpropyl, phenylisopropyl, phenylbutyl, phenylisobutyl, phenyl t-butyl, menaphthyl, naphthylethyl, naphthylpropyl,naphthylbutyl, dihydromenaphthyl, dihydronaphthylethyl,dihydronaphthylpropyl, dihydronaphthylbutyl, tetrahydromenaphthyl,tetrahydronaphthylethyl, tetrahydronaphthylpropyl,tetrahydronaphthylbutyl and the like.

In the present invention, the term “5- to 10-membered heterocyclyl”represents 5- to 10-membered, monocyclic or bicyclic, alicyclicheterocyclyl containing heteroatoms selected from the group consistingof N, O and S. Said heterocyclyl includes, but is not limited to,tetrahydrofuryl, tetrahydrothienyl, 1,3-dioxolanyl, 1,3-dithiolanyl,tetrahydropyranyl, 1,4-dioxanyl, 1,3-dioxanyl, 1,3-oxathianyl,dihydrofuryl, dihydrothienyl, dihydropyranyl, dihydrooxazolyl,dihydrothiazolyl and the like.

In the present invention, the term “5- to 10-membered heteroaryl group”represents 5- to 10-membered, aromatic, monocyclic or bicyclicheterocyclyl containing heteroatoms selected from the group consistingof N, O and S. Said heteroaryl group includes, but is not limited to,e.g. pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, furyl, imidazolyl,pyranyl, pyrazolyl, oxazolyl, isooxazolyl, thiazolyl, isothiazolyl,thienyl, purinyl, benzofuranyl, benzothiophenyl, diazinyl,isobenzothiophenyl, isobenzofuranyl, indolyl, isoindolyl, quinolinyl,isoquinolinyl and the like.

In the present invention, the term “halogen” represents fluorine,chlorine, bromine, iodine.

In the present invention, the term “pharmaceutically acceptable salt”represents a salt formed by reacting a pharmaceutically acceptablenontoxic acid with the alkaline moiety of the compound of the formula(I) or (I-1) of the present invention, including, e.g. hydrochlorides,acetates, hydrobromides, sulfates, bisulfates, carbonates, bicarbonates,sulfites, phosphates, biphosphates, oxalates, malonates, pentanoate,borates, p-toluene sulphonates, mesylates, tartrates, benzoates,lactates, citrates, maleates, fumarates, malates, salicylates,amygdalates, succinates, gluconates, lactobionates and the like. Suchsalt may be prepared by the method well known by those skilled in theart.

In one embodiment of the compound of the formula (I) or (I-1) of thepresent invention, R₃ represents H or C₃-C₆ alkyl.

In one preferred embodiment of the compound of the formula (I) or (I-1)of the present invention, R₁ represents an unsubstituted orR₄-substituted C₁-C₆ alkyl, wherein R₄ represents halogen, C₁-C₄ alkyl,C₁-C₄ alkoxyl, halogenated C₁-C₄ alkyl, halogenated C₁-C₄ alkoxyl,hydroxyl, hydroxyl C₁-C₄ alkyl, carboxyl, nitro, cyano, C₁-C₄ alkylthio,C₁-C₄-alkyl-CO-_(o)

In one preferred embodiment of the compound of the formula (I) of thepresent invention, R₂ represents an unsubstituted or R₅-substitutedC₃-C₈, preferably C₃-C₆ alkyl, an unsubstituted or R₅-substituted C₃-C₆cycloalkyl, an unsubstituted or R₆-substituted phenyl-C₁-C₄ alkyl, anunsubstituted or R₆-substituted 5- to 6-membered heteroaryl-C₁-C₄ alkyl,or an unsubstituted or R₆-substituted 5- to 6-memberedheterocyclyl-C₁-C₄ alkyl, wherein R₅ is selected from the groupconsisting of C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl, hydroxyl C₁-C₄alkyl, carboxyl, nitro, cyano, C₁-C₄ alkylthio and C₁-C₄ alkyl-CO—; andR₆ is selected from the group consisting of halogen, C₁-C₄ alkyl, C₁-C₄alkoxyl, hydroxyl, hydroxyl C₁-C₄ alkyl, carboxyl, nitro, cyano, C₁-C₄alkylthio and C₁-C₄ alkyl-CO—.

In one preferred embodiment of the compound of the formula (I-1) of thepresent invention, R_(2a) represents an unsubstituted or R₅-substitutedC₃-C₈, preferably C₃-C₆ alkyl, an unsubstituted or R₅-substituted C₃-C₆cycloalkyl, an unsubstituted or R₆-substituted phenyl-C₂-C₄ alkyl, anunsubstituted or R₆-substituted 5- to 6-membered heteroaryl-C₁-C₄ alkyl,or an unsubstituted or R₆-substituted 5- to 6-memberedheterocyclyl-C₁-C₄ alkyl, wherein R₅ is selected from the groupconsisting of C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl, hydroxyl C₁-C₄alkyl, carboxyl, nitro, cyano, C₁-C₄ alkylthio and C₁-C₄ alkyl-CO—; andR₆ is selected from the group consisting of halogen, C₁-C₄ alkyl, C₁-C₄alkoxyl, hydroxyl, hydroxyl C₁-C₄ alkyl, carboxyl, nitro, cyano, C₁-C₄alkylthio and C₁-C₄ alkyl-CO—.

In one preferred embodiment of the compound of the formula (I) of thepresent invention, R₁ represents an unsubstituted or R₄-substitutedC₁-C₆ alkyl; R₂ represents an unsubstituted or R₅-substituted C₃-C₆alkyl, an unsubstituted or R₅-substituted C₃-C₆ cycloalkyl, anunsubstituted or R₆-substituted 5- to 6-membered heteroaryl-C₁-C₄ alkyl,an unsubstituted or R₆-substituted phenyl-C₁-C₄ alkyl, or anunsubstituted or R₆-substituted 5- to 6-membered heterocyclyl-C₁-C₄alkyl; and R₃ represents H or C₃-C₆ alkyl; wherein R₄ representshalogen, C₁-C₄ alkyl, C₁-C₄ alkoxyl, halogenated C₁-C₄ alkyl,halogenated C₁-C₄ alkoxyl, hydroxyl, hydroxyl C₁-C₄ alkyl, carboxyl,nitro, cyano, C₁-C₄ alkylthio, C₁-C₄-alkyl-CO—; R₅ is selected from thegroup consisting of C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl, hydroxyl C₁-C₄alkyl, carboxyl, nitro, cyano, C₁-C₄ alkylthio and C₁-C₄ alkyl-CO—; andR₆ is selected from the group consisting of halogen, C₁-C₄ alkyl, C₁-C₄alkoxyl, hydroxyl, hydroxyl C₁-C₄ alkyl, carboxyl, nitro, cyano, C₁-C₄alkylthio and C₁-C₄ alkyl-CO—.

In one preferred embodiment of the compound of the formula (I-1) of thepresent invention, R₁ represents an unsubstituted or R₄-substitutedC₁-C₆ alkyl; R_(2a) represents an unsubstituted or R₅-substituted C₃-C₆alkyl, an unsubstituted or R₅-substituted C₃-C₆ cycloalkyl, anunsubstituted or R₆-substituted 5- to 6-membered heteroaryl-C₁-C₄ alkyl,an unsubstituted or R₆-substituted phenyl-C₂-C₄ alkyl, or anunsubstituted or R₆-substituted 5- to 6-membered heterocyclyl-C₁-C₄alkyl; and R₃ represents H or C₃-C₆ alkyl; wherein R₄ representshalogen, C₁-C₄ alkyl, C₁-C₄ alkoxyl, halogenated C₁-C₄ alkyl,halogenated C₁-C₄ alkoxyl, hydroxyl, hydroxyl C₁-C₄ alkyl, carboxyl,nitro, cyano, C₁-C₄ alkylthio, or C₁-C₄-alkyl-CO—; R₅ is selected fromthe group consisting of C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl, hydroxylC₁-C₄ alkyl, carboxyl, nitro, cyano, alkylthio and C₁-C₄ alkyl-CO—; andR₆ is selected from the group consisting of halogen, C₁-C₄ alkyl, C₁-C₄alkoxyl, hydroxyl, hydroxyl C₁-C₄ alkyl, carboxyl, nitro, cyano, C₁-C₄alkylthio and C₁-C₄ alkyl-CO—.

In another preferred embodiment of the compound of the formula (I) ofthe present invention, R₁ represents C₁-C₆ alkyl; R₂ represents C₃-C₆alkyl, C₅-C₆ cycloalkyl, an unsubstituted or R₆-substituted phenyl-C₁-C₄alkyl, an unsubstituted or R₆-substituted 5- to 6-memberedheteroaryl-C₁-C₄ alkyl, or an unsubstituted or R₆-substituted 5- to6-membered heterocyclyl-C₁-C₄ alkyl, wherein R₆ is selected from thegroup consisting of halogen, C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl,hydroxyl C₁-C₄ alkyl and C₁-C₄ alkylthio.

In another preferred embodiment of the compound of the formula (I-1) ofthe present invention, R₁ represents C₁-C₆ alkyl; R_(2a) representsC₃-C₆ alkyl, C₅-C₆ cycloalkyl, an unsubstituted or R₆-substitutedphenyl-C₂-C₄ alkyl, an unsubstituted or R₆-substituted 5- to 6-memberedheteroaryl-C₁-C₄ alkyl, or an unsubstituted or R₆-substituted 5- to6-membered heterocyclyl-C₁-C₄ alkyl, wherein R₆ is selected from thegroup consisting of halogen, C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl,hydroxyl C₁-C₄ alkyl and C₁-C₄ alkylthio.

In another preferred embodiment of the compound of the formula (I) ofthe present invention, R₁ represents C₁-C₄ alkyl; R₂ represents C₃-C₆alkyl, C₅-C₆ cycloalkyl, or C₁-C₄ alkyl-substituted or C₁-C₄alkoxyl-substituted phenyl-C₁-C₄ alkyl, unsubstituted or C₁-C₄alkyl-substituted or C₁-C₄ alkoxyl-substituted 5- to 6-memberedheteroaryl-C₁-C₄ alkyl, or unsubstituted or C₁-C₄ alkyl-substituted orC₁-C₄ alkoxyl-substituted 5- to 6-membered heterocyclyl-C₁-C₄ alkyl; andR₃ represents H or C₃-C₄ alkyl.

In another preferred embodiment of the compound of the formula (I-1) ofthe present invention, R₁ represents C₁-C₄ alkyl; R_(2a) representsC₄-C₆ alkyl, C₅-C₆ cycloalkyl, C₁-C₄ alkyl-substituted or C₁-C₄alkoxyl-substituted phenyl-C₂-C₄ alkyl, unsubstituted or C₁-C₄alkyl-substituted or C₁-C₄ alkoxyl-substituted 5- to 6-memberedheteroaryl-C₁-C₄ alkyl, or unsubstituted or C₁-C₄ alkyl-substituted orC₁-C₄ alkoxyl-substituted 5- to 6-membered heterocyclyl-C₁-C₄ alkyl; andR₃ represents H or C₃-C₄ alkyl.

In another preferred embodiment of the compound of the formula (I) ofthe present invention, R₁ represents methyl, ethyl, n-propyl, isopropylor butyl; R₂ represents n-hexyl, cyclohexyl, 1-phenylethyl,2-phenylethyl, 3-phenylpropyl, 4-phenylbutyl, methoxylphenylethyl,2-thienylethyl, furylmethyl, or tetrahydrofurylmethyl; and R₃ representsH or C₃-C₄ alkyl.

In another preferred embodiment of the compound of the formula (I-1) ofthe present invention, R₁ represents methyl, ethyl, n-propyl, isopropylor butyl; R_(2a) represents n-hexyl, cyclohexyl, 2-phenylethyl,3-phenylpropyl, 4-phenylbutyl, methoxylphenylethyl, 2-thienylethyl,furylmethyl, or tetrahydrofurylmethyl; and R₃ represents H or C₃-C₄alkyl.

The particularlly preferred compounds of the formula (I) or (I-1) (whenR₂=R_(2a) in the formula (I)) of the present invention comprise thefollowing compounds and pharmaceutically acceptable salts thereof:

Name of compounds R₁ R₂ or R_(2a) R₃ 2-propylthio-6-n-hexylamino-9-β-D-propyl n-hexyl H ribofuranosyl purine2-ethylthio-6-cyclohexylamino-9-β-D- ethyl cyclohexyl H ribofuranosylpurine 2-propylthio-6-cyclohexylamino-9-β-D- propyl cyclohexyl Hribofuranosyl purine 2-isopropylthio-6-cyclohexylamino-9-β-D- isopropylcyclohexyl H ribofuranosyl purine 2-butylthio-6-cyclohexylamino-9-β-D-butyl cyclohexyl H ribofuranosyl purine 2-ethylthio-6-benzylamino-9-β-D-ethyl benzyl H ribofuranosyl purine 2-propylthio-6-benzylamino-9-β-D-propyl benzyl H ribofuranosyl purine 2-butylthio-6-benzylamino-9-β-D-butyl benzyl H ribofuranosyl purine 2-ethylthio-6-(1-phenylethyl)amino-ethyl 1- H 9-β-D-ribofuranosyl purine phenylethyl2-propylthio-6-([4-methoxylbenzyl]- propyl 4-methoxyl- Hamino)-9-β-D-ribofuranosyl purine benzyl2-methylthio-6-phenylethylamino-9-β-D- methyl phenylethyl Hribofuranosyl purine 2-ethylthio-6-phenylethylamino-9-β-D- ethylphenylethyl H ribofuranosyl purine2-propylthio-6-phenylethylamino-9-β-D- propyl phenylethyl Hribofuranosyl purine 2-butylthio-6-phenylethylamino-9-β-D- butylphenylethyl H ribofuranosyl purine2-methylthio-6-([4-methoxylphenylethyl]- methyl 4-methoxyl- Hamino)-9-β-D-ribofuranosyl purine phenylethyl2-ethylthio-6-([4-methoxylphenylethyl]- ethyl 4-methoxyl- Hamino)-9-β-D-ribofuranosyl purine phenylethyl2-propylthio-6-([4-methoxylphenylethyl]- propyl 4-methoxyl- Hamino)-9-β-D-ribofuranosyl purine phenylethyl2-butylthio-6-([4-methoxylphenylethyl]- butyl 4-methoxyl- Hamino)-9-β-D-ribofuranosyl purine phenylethyl2-ethylthio-6-([3-methoxylphenylethyl]- ethyl 3-methoxyl- Hamino)-9-β-D-ribofuranosyl purine phenylethyl2-propylthio-6-([3-methoxylphenylethyl] propyl 3-methoxyl- Hamino)-9-β-D-ribofuranosyl purine phenylethyl2-ethylthio-6,6-(dibutylamino)-9-β-D- ethyl butyl butyl ribofuranosylpurine 2-ethylthio-6-(2-thienylethyl)amino- ethyl 2- H9-β-D-ribofuranosyl purine thienylethyl2-propylthio-6-(2-thienylethyl)amino- propyl 2- H 9-β-D-ribofuranosylpurine thienylethyl 2-ethylthio-6-(3-phenylpropyl)amino- ethyl 3-phenyl-H 9-β-D-ribofuranosyl purine propyl 2-ethylthio-6-(4-phenylbutyl)amino-ethyl 4-phenyl- H 9-β-D-ribofuranosyl purine butyl2-ethylthio-6-(2-furylmethyl)amino- ethyl 2-furyl- H 9-β-D-ribofuranosylpurine methyl 2-ethylthio-6-(2-tetrahydrofurylmethyl)- ethyl2-tetrahydro- H amino-9-β-D-ribofuranosyl purine furylmethyl

In one embodiment of the process for preparing the compound of thegeneral formula (I) or (I-1) (when R₂=R₂, in the general formula (I)),the process may comprise the following specific steps:

a) adding dried guanosine 1, acetic anhydride or acyl halide and organicbase, such as triethylamine in an molar ratio of about 1:3.5:4 intoanhydrous acetonitrile successively, upon being fully dissolved, addingto the solution 4-dimethylamino pyridine in a catalytic amount, sharplystirring at room temperature for 0.5 h, then evaporating the solventunder reduced pressure, and then recrystallizing the residue withisopropanol to obtain an intermediate 2;

b) successively adding the intermediate 2, anhydrous Et₄NCl, POCl₃ andN,N-dimethylaniline in an molar ratio of about 1:3:4.5:1.5 into a mixedsolvent of anhydrous acetonitrile and anhydrous 1,2-dichloroethane in avolume ratio of 1:2, heating and refluxing the mixture for 20-25 min,then slowly pouring the resulting mixture into brash ice, on being fullydissolved, separating the liquid, extracting, and combining the obtainedorganic phases, adjusting the pH to about 7.0 with 5% sodium bicarbonatesolution,re-separating the liquid and extracting, drying the organicphase, and then distilling the organic phase under reduced pressure,recrystallizing the residue with ethanol to obtain a white crystallineintermediate 3;

c) adding the intermediate 3 and the corresponding disulfide in a molarratio of 1:5 into anhydrous acetonitrile successively, and then stirringthe mixture at room temperature and feeding the protecting gas for about20-30 min, to the reaction system immediately adding 6.2 mol of isoamylnitrite (i-AmONO), continuously stirring, then reacting at 60-80° C. for4-8 h, separating the resulting mixture by the silica gel columnchromatography to obtain an intermediate 4;

d) successively adding the intermediate 4, the corresponding amine andorganic base (e.g. triethylamine, sodium hydride, potassium tertbutoxideand the like) in a molar ratio of about 1:5:1 into an anhydrous alcohol,e.g. ethanol or methanol, heating and refluxing the mixture for 4-8 h,adding metal sodium or potassium in a catalytic amount after it ismonitored by TLC that the starting materials disappear, continuouslyheating and refluxing the reaction mixture till it is monitored by TLCthat the reaction is completed, and then evaporating the solvent underreduced pressure, separating the residue by the silica gel columnchromatography neutralized with alkaline, recrystallizing to obtain thetarget product compound of the formula (I) or (I-1) (when R₂=R_(2a) inthe formula (I)).

It has been proved by tests that the compound of the formula (I) of thepresent invention has notable activities of anti-platelet aggregation,and can be used for the treatment and/or prevention of various diseasesassociated with platelet aggregation.

Thus the present invention further provides a pharmaceutical compositioncontaining the compound of the formula (I-1) or a pharmaceuticallyacceptable salt thereof and a pharmaceutically acceptable carrier.

The pharmaceutically acceptable carrier may include the conventionalpharmaceutically acceptable carriers in the art, e.g. fillers, binders,disintegrating agents, lubricants, solvents, solubilizers, substratesfor transdermal patches, substrates for suppository and the like,including, but not limited to starch, powdered sugar, calcium phosphate,magnesium stearate, talc powder, dextrin, cellulose and derivativesthereof, microcrystalline cellulose, polyethylene glycol, normal saline,glucose solution, conventional substrates for transdermal patches suchas acrylic pressure-sensitive adhesives, siloxane (silicone)pressure-sensitive adhesives, polyisobutylene pressure-sensitiveadhesives or combinations thereof, cocoa butter, paraffin and the like.

The pharmaceutical composition of the present invention may alsocomprise various other common additives, e.g. preservatives, emulsifyingagents, suspending agents, flavoring agents and the like.

The pharmaceutical composition of the present invention may be preparedas any suitable pharmaceutically acceptable dosage form, e.g. tablets,capsules, pills, granular formulations, syrups, injections, solutions,suspensions, transdermal patches, suppository and the like.

The compound of the formula (I) of the present invention or apharmaceutically acceptable salt thereof may be administered to mammals,e,g. human beings, via any effective routes, including oral,intravenous, intraperitoneal, intramuscular, topical, transdermal,intraocular, intranasal, inhalation, subcutaneous, intramuscular,buccal, sublingual, rectal administration and the like. They may beadministered alone, or in combination with other active ingredients. Thecompound of the formula (1) of the present invention or apharmaceutically acceptable salt thereof is in an effective amount offrom about 0.01 mg per kg weight per day(mg/kg/day) to about 100mg/kg/day, e.g. from about 0.1 mg/kg/day to about 80 mg/kg/day. Thepreferred amount can be determined by those skilled in the art. Forexample, the doctors in charge can readily determine the effectiveamount by the conventional methods and by observing the results obtainedunder similar circumstances. While the effective amount of the compoundof the present invention is determined, many factors should be takeninto consideration by the doctors in charge, including, but not limitedto specific compounds to be administered; combined administration withother pharmaceuticals; kind, size, age and general health condition ofmammals; severity of the disease; response of individual patients;method of administration, bioavailability characteristics of theformulation to be administered; dose scheme to be selected; use of otherconcomitant drugs and other related situations. The present inventionfurther provides the use of the compound of the formula (I) of thepresent invention in the manufacture of a medicament for the treatmentof diseases associated with platelet aggregation.

The diseases associated with platelet aggregation include, but are notlimited to, e.g. thrombotic diseases, viral diseases having ahypercoagulable state, neoplastic diseases, coronary heart disease,stroke, hypertension, leukemia, disseminated intravascular coagulation(DIC) and the like.

Embodiments

The present invention is further and specifically explained by thefollowing examples. However, these examples are merely used forillustrating the present invention, and they shall not be deemed tolimit the protection scope of the present invention.

In the examples, the abbreviation MeOH represents methanol; EtOAcrepresents ethyl acetate; Et₃N represents triethylamine; Et₄NClrepresents tetraethylammonium chloride; P.E. represnts petroleum ether(having a boiling range of from 60 to 90° C.); CDCl₃ representsdeuterated chloroform; DMSO-d₆ represents deuterated dimethylsulphoxide; ADP represents adenosine diphosphate; AA representsarachidonic acid; TLC represent thin-layer chromatography; i-AmONOrepresents isoamyl nitrite; Ac₂O represents acetic anhydride; R₁SSR₁represents disulfides; EtOH represents ethanol.

¹H NMR is measured with Varian Mercury 200 (200 MHz), Varian MercuryPlus 300 (300 MHz), Bruker 400 AMX (400 MHz) or Bruker 600 AMX (600 MHz)nuclear magnetic resonance apparatus, wherein s represents singlets; brs represents broadsinglets; d represents doublets; t representstriplets; q represents quartets; sextet represents sextets; heptetrepresents heptets; m represents multiplets; and Ar represents aryl.

I. Preparation Examples of compounds EXAMPLE 1 Preparation of2-amino-6-hydroxyl-9-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosyl)purine (2)

At room temperature, dried guanosine 1 (11.3 g, 40 mmol), triethylamine(22.9 mL, 158.4 mmol) and acetic anhydride (13.6 mL, 144 mmol) wererespectively dissolved in 500 ml anhydrous acetonitrile, and4-dimethylamino pyridine (366 mg, 3 mmol) was added therein. Theresultant mixed solution was sharply stirred at room temperature for 30min, and then continuously stirred for 10 min after 5 ml anhydrousmethanol was added. The solvent was evaporated under reduced pressure,and the resultant solid was recrystallized with 180 mL isopropanol toobtain white crystals 2 (15.7 g, 96%), m.p 229-231° C.; ¹H NMR (300 MHz,DMSO-d₆) δ 10.75 (1H, br s),7.94 (1H, s), 6.55 (2H, br s), 5.98 (1H, d,J=4.8 Hz), 5.79 (1H, t, J=5.5 Hz), 5.59 (1H, t, J=5.5 Hz), 4.40-4.24(3H, m), 2.11 (3H, s), 2.04 (3H, s), 2.03 (3H, s).

EXAMPLE 2 Preparation of2-amino-6-chloro-9-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosyl)purine (3)

Anhydrous acetonitrile (15 mL) and anhydrous 1,2-dichloroethane (30 mL)were placed into a 100 ml three-necked bottle. While stirring at roomtemperature, 10.0 g (24.4 mmol) compound 2, 11.0 g (66.4 mmol) Et₄NCland 16.8 g (10.0 mL, 109.6 mmol) POCl₃, and 4.78 g (5.0 mL, 35.1 mmol)N,N-dimethylaniline were successively added therein, and rapidly heatedto reflux. After holding 20-25 min, the resultant mixed solution wasslowly and dropwise added to brash ice and stirred, and 10 mL1,2-dichloroethane was supplemented. After brash ice was completelydissolved, the resultant mixed solution was poured into a 250 mLseparating funnel for separation. After the aqueous phase was extractedthree times with 50 mL 1,2-dichloroethane, the organic phases werecombined together and adjusted to a pH of 7 with cold 5% sodiumcarbonate solution, then a liquid separation was carried out. Theorganic phase was washed three times with 50 mL cold water, and driedover anhydrous MgSO₄, filtered and evaporated under reduced pressure toremove the solvent, and then 70 mL anhydrous ethanol was added to theresidue which was recrystallized therefrom as a white crystal 3 (8.56 g,with a yield of 81.9%), m.p 155-156° C.; ¹H NMR (600 MHz, CDCl₃) δ 7.88(1H, s), 5.99 (1H, d, J=4.8 Hz), 5.93 (1H, t, J=4.9 Hz), 5.72 (1H, t,J=4.9 Hz), 5.27 (2H, br s), 4.35-4.44 (3H, m), 2.13 (3H, s), 2.09 (3H,s), 2.07 (3H, s).

The intermediate compound 4 was prepared according to the followingreaction route.

EXAMPLE 3 Preparation of2-methylthio-6-chloro-9-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosyl)purine(4a)

Compound 3 (2.5 g, 5.85 mmol) and dimethyl disulfide (29.25 mmol) wererespectively added to 35 mL anhydrous acetonitrile, then nitrogen gaswas fed to the mixed solution, and at room temperature, the mixedsolution was stirred for 30 min, and then isoamyl nitrite (4.25 g, 36.3mmol) was immediately added to the mixed solution. The resultant mixedsolution was continuously stirred at room temperature for 10 min, andthen transferred to an oil bath at 60° C., and heated for 4-8 hours.After it was detected with TLC (EtOAc-P.E., 1:1) that the startingmaterials disappeared, the solvent was evaporated under reducedpressure, and the residue was isolated by column chromatography (silicagel, EtOAc-P.E., 2:3, 1:1) to obtain a light yellow oily liquid 4a, witha yield of 66%; ¹H NMR (300 MHz, CDCl₃): δ 8.09 (1H, s), 6.09 (1H, d,J=4.5 Hz), 5.97 (1H, t, J=5.4 Hz), 5.62 (1H, t, J=5.4 Hz), 4.45-4.43(1H, m), 4.42-4.39 (1H, m), 4.32-4.26 (1H, m), 2.61 (3H, s), 2.12 (3H,s), 2.08 (3H, s), 2.06 (3H, s).

EXAMPLE 4 Preparation of2-ethylthio-6-chloro-9-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosyl)purine(4b)

The preparation method above-mentioned in Example 3 was used, exceptthat dimethyl disulfide was replaced with diethyl disulfide, and theresidue was isolated by column chromatography (silica gel, EtOAc-P.E.,2:3, 1:1) to obtain a light yellow liquid 4b, with a yield of 62%; ¹HNMR (300 MHz, CDCl₃): δ 8.10 (1H, s), 6.09 (1H, d, J =4.5 Hz), 5.93 (1H,t, J=5.4 Hz), 5.59 (1H, t, J=5.4 Hz), 4.45-4.43 (1H, m), 4.42-4.40 (1H,m), 4.32-4.30 (1H, m), 3.21 (2H, q, J=7.3 Hz), 2.14 (3H, s), 2.09 (6H,s), 1.41 (3H, t, J=7.3 Hz).

EXAMPLE 5 Preparation of2-propylthio-6-chloro-9-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosyl)purine(4c)

The preparation method above-mentioned in Example 3 was used, exceptthat dimethyl disulfide was replaced with dipropyl disulfide, and theresidue was isolated by column chromatography (silica gel, EtOAc-P.E.,2:3, 1:1) to obtain a light yellow liquid 4c, with a yield of 57%; ¹HNMR (600 MHz, DMSO-d₆): δ 8.69 (1H, s), 6.29 (1H, d, J=4.5 Hz), 6.01(1H, t, J=5.4 Hz), 5.58 (1H, t, J=5.4), 4.42-4.40 (1H, m), 4.39-4.38(1H, m), 4.25-4.22 (1H, m), 3.19 (2H, t, J=7.3 Hz), 2.11 (3H, s), 2.06(3H, s), 1.97 (3H, s), 1.77-1.71 (2H, m), 1.01 (3H, t, J=7.3 Hz).

EXAMPLE 6 Preparation of2-isopropylthio-6-chloro-9-(2′,3′,5′-tri-oxy-acetyl-β-D-ribofuranosyl)purine(4d)

The preparation method above-mentioned in Example 3 was used, exceptthat dimethyl disulfide was replaced with diisopropyl disulfide, and theresidue was isolated by column chromatography (silica gel, EtOAc-P.E.,2:3, 1:1) to obtain a light yellow liquid 4d, with a yield of 43%; ¹HNMR (300 MHz, CDCl₃): δ 8.10 (1H, s), 6.11 (1H, d, J=4.8 Hz), 5.90 (1H,t, J=5.4 Hz), 5.57 (1H, t, J=5.4 Hz), 4.44-4,42 (1H, m), 4.40-4.38 (1H,m), 4.33-4.28 (1H, m), 4.00 (1H, heptet, J=7.3 Hz), 2.13 (3H, s), 2.09(3H, s), 2.08 (3H, s), 1.44 (6H, d, J=7.3 Hz).

EXAMPLE 7 Preparation of2-butylthio-6-chloro-9-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosyl)purine(4e)

The preparation method above-mentioned in Example 3 was used, exceptthat dimethyl disulfide was replaced with dibutyl disulfide, and theresidue was isolated by column chromatography (silica gel, EtOAc-P.E.,2:3, 1:1) to obtain a light yellow liquid 4e, with a yield of 50%; NMR(600 MHz, CDCl₃): δ 8.11 (1H, s), 6.14 (1H, d, J=4.8 Hz), 5.89 (1H, t,J=5.4 Hz), 5.58 (1H, t, J=5.3), 4.45-4.43 (1H, m), 4.42-4.40 (1H, m),4.34-4.31 (1H, m), 3.20 (2H, t, J=7.3), 2.13 (3H, s), 2.10 (3H, s), 2.08(3H, s), 1.76-1.71 (2H, m), 1.51-1.45 (2H, m), 0.95 (3H, t, J=7.3 Hz).

The compound of the formula (I) or (I-1) (when R₂=R_(2a) in the formula(I)) of the present invention was prepared according to the followingreaction route.

EXAMPLE 8 Preparation of 2-propylthio-6-n-hexylamino-9-β-D-ribofuranosylpurine

Compound 4e (2 mmol) was dissolved in 20 mL anhydrous ethanol, and thentriethylamine (1 mmol) and n-hexylamine (10 mmol) were addedsuccessively and refluxed for 8 hours. After it was detected with TLC(MeOH-EtOAc, 1:15, v/v) that the starting materials disappeared, acatalytic amount of the metal sodium (0.05mmol) was added to remove theprotecting group of acetyl. After it was monitored by TLC that thereaction was completed, the solvent was evaporated under reducedpressure, and the residue was isolated by column chromatography(Et₃N-neutralized silica gel, gradient elution, MeOH-EtOAc, 1:30, 1:15,v/v). Upon recrystallizing with methanol and washing with water, thetitle compound was obtained as white crystals with a yield of 84%, m.p186-188° C.; NMR(600 MHz, DMSO-d₆): δ 8.19 (1H, s), 7.92 (1H, br s,),5.80 (1H, d, J=6.0 Hz), 5.37 (1H, d, J=6.0 Hz), 5.13 (1H, d, J=4.8 Hz),5.06 (1H, t, J=5.4 Hz), 4.58 (1H, ddd, J=5.6, 5.8, 6.0 Hz), 4.13 (1H,ddd, J=3.8, 4.8, 5.6 Hz), 3.92 (1H, ddd, J=3.8, 4.4, 5.4 Hz), 3.66-3.63(1H, m), 3.55-3.52 (1H, m), 3.44 (2H, br s), 3.07 (2H, t, J=7.3 Hz),1.72-1.67 (2H, m), 1.60-1.56 (2H, m), 1.28 (6H, m), 0.99 (3H, t, J=7.3Hz), 0.86 (3H, t, J=6.5 Hz).

EXAMPLE 9 Preparation of2-ethylthio-6-cyclohexylamino-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4b reacted with cyclohexylamine for 10 hours; theresidue was separated by column chromatography (Et₃N-neutralized silicagel, gradient elution, MeOH-EtOAc, 1:30, 1:15, v/v) and recrystallizedwith EtOAc, the title compound was obtained as white crystals with ayield of 80%, m.p 166-168° C.; ¹H NMR (600 MHz, CDCl₃): δ 7.74 (1H, s),6.10 (1H, br s), 5.76 (1H, d, J=6.7 Hz), 5.43 (1H, d, J=6.1 Hz), 5.19(1H, d, J=4.8 Hz), 5.03 (1H, t, J=5.4 Hz), 4.43 (1H, br s), 4.29 (1H, brs), 4.11-4.05 (1H, m), 3.94-3.92 (1H, m), 3.76-3.74 (1H, m), 3.08 (1H,dt, J=7.3, 14.6 Hz), 2.94 (1H, dt, J=7.3, 14.6 Hz), 1.81-1.65 (9H, m),1.34 (3H, t, J=7.3 Hz), 1.27-1.25 (2H, m).

EXAMPLE 10 Preparation of2-propylthio-6-cyclohexylamino-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4c reacted with cyclohexylamine for 7 hours; theresidue was separated by column chromatography (Et₃N-neutralized silicagel, gradient elution, MeOH-EtOAc, 1:30, 1:15, v/v) and recrystallizedwith EtOAc, the title compound was obtained as white crystals with ayield of 82%, m.p 162-164° C.; ¹H NMR (300 MHz, DMSO-d₆): δ 8.21 (1H,s), 7.72 (1H, br s), 5.81 (1H, d, J=5.9 Hz), 5.42 (1H, d, J=6.1 Hz),5.18 (1H, d, J=4.8 Hz), 5.10 (1H, t, J=5.4 Hz), 4.59 (1H, ddd, J=5.0,5.9, 6.1 Hz), 4.14 (1H, ddd, J=3.4, 4.8, 5.0 Hz), 3.94 (1H, ddd, J=3.4,4.6, 6.0 Hz), 3.69-3.62 (1H, m), 3.58-3.51 (1H, m), 3.04 (2H, t, J=7.3Hz), 1.90-1.87 (2H, m), 1.76-1.73 (2H, m), 1.71-1.28 (9H, m), 0.99 (3H,t, J=7.3 Hz).

EXAMPLE 11 Preparation of2-isopropylthio-6-cyclohexylamino-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4d reacted with cyclohexylamine for 9 hours; theresidue was separated by column chromatography (Et₃N-neutralized silicagel, gradient elution, MeOH-EtOAc, 1:30, 1:15, v/v) and recrystallizedwith EtOAc, the title compound was obtained as white crystals with ayield of 77%, m.p 136-138° C.; ¹H NMR (400 MHz, DMSO-d₆): δ 8.20 (1H,s), 7.72 (1H, br s), 5.80 (1H, d, J=5.8 Hz), 5.39 (1H, d, J=6.1 Hz),5.15 (1H, d, J=4.8 Hz), 5.07 (1H, t, J=5.4 Hz), 4.57 (1H, ddd, J=5.6,5.8, 6.1 Hz), 4.00 (1H, ddd, J=3.7, 4.7, 5.6 Hz), 3.91 (1H, ddd, J=3.5,4.7, 6.1 Hz), 3.87-3.82 (1H, m), 3.66-3.61 (1H, m), 3.52 (1H, heptet,J=6.1 Hz), 1.88-1.86 (2H, m), 1.76-1.73 (2H, m), 1.63-1.60 (1H, m), 1.37(6H, d, J=6.1 Hz), 1.32-1.11 (6H, m).

EXAMPLE 12 Preparation of2-butylthio-6-cyclohexylamino-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4e reacted with cyclohexylamine for 9 hours; theresidue was separated by column chromatography (Et₃N-neutralized silicagel, gradient elution, MeOH-EtOAc, 1:30, 1:15, v/v) and recrystallizedwith EtOAc, the title compound was obtained as white crystals with ayield of 88%, m.p 138-140° C.; ¹H NMR (400 MHz, DMSO-d₆): δ 8.20 (1H,s), 7.72 (1H, br s), 5.80 (1H, d, J=5.6 Hz), 5.40 (1H, d, J=5.8 Hz),5.15 (1H, d, J=4.8 Hz), 5.08 (1H, t, J=5.4, 5.6 Hz), 4.57 (1H, ddd,J=4.9, 5.6, 5.8 Hz), 4.12 (1H, ddd, J=3.2, 4.5, 4.9 Hz), 4.03 (1H, brs), 3.91 (1H, ddd, J=3.2, 4.6, 6.0 Hz), 3.67-3.62 (1H, m), 3.56-3.50(1H, m), 3.06 (2H, t, J=7.3 Hz), 1.89-1.87 (2H, m), 1.77-1.74 (2H, m),1.68-1.61 (3H, m), 1.47-1.42 (2H, m), 1.38-1.11 (6H, m), 0.92 (3H, t,J=7.3 Hz).

EXAMPLE 13 Preparation of 2-ethylthio-6-benzylamino-9-β-D-ribofuranosylpurine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4b reacted with benzylamine for 8 hours; theresidue was separated by column chromatography (Et₃N-neutralized silicagel, gradient elution, MeOH-EtOAc, 1:50, 1:25, v/v) and recrystallizedwith EtOAc, the title compound was obtained as white crystals with ayield of 82%, m.p. 172-174° C.; ¹H NMR: (600 MHz, DMSO-d₆): δ 8.51 (1H,br s), 8.24 (1H, s), 7.33-7.28 (4H, m), 7.21 (1H, t, J=7.0 Hz), 5.82(1H, d, J=5.9 Hz), 5.39 (1H, d, J=6.1 Hz), 5.15 (1H, d, J=4.8 Hz), 5.04(1H, t, J=5.4 Hz), 4.66 (2H, br s), 4.58 (1H, ddd, J=5.6, 5.9, 6.1 Hz),4.12 (1H, ddd, J=3.4, 4.7, 5.6 Hz), 3.91 (1H, ddd, J=3.4, 4.7, 5.7 Hz),3.65-3.62 (1H, m), 3.55-3.51 (1H, m), 3.00 (2H, q, J=7.3 Hz), 1.28 (3H,t, J=7.3 Hz).

EXAMPLE 14 Preparation of 2-propylthio-6-benzylamino-9-β-D-ribofuranosylpurine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4c reacted with benzylamine for 8 hours; theresidue was separated by column chromatography (Et₃N-neutralized silicagel, gradient elution, MeOH-EtOAc, 1:50, 1:25, v/v) and recrystallizedwith EtOAc, the title compound was obtained as white crystals with ayield of 79%, m.p 168-170° C.; ¹H NMR: (600 MHz, DMSO-d₆): δ 8.51 (1H,br s), 8.24 (1H, s), 7.33-7.28 (4H, m), 7.21 (1H, t, J=7.0 Hz), 5.82(1H, d, J=5.9 Hz), 5.39 (1H, d, J=6.1 Hz), 5.15 (1H, d, J=4.8 Hz), 5.04(1H, t, J=5.4 Hz), 4.66 (2H, br s), 4.58 (1H, ddd, J=5.4, 5.7, 6.0 Hz),4.12 (1H, ddd, J=3.2, 4.5, 5.4 Hz), 3.91 (1H, ddd, J=3.2, 4.3, 5.8 Hz),3.65-3.62 (1H, in), 3.55-3.51 (1H, m), 3.00 (2H, q, J=7.3 Hz), 1.28 (3H,t, J=7.3 Hz).

EXAMPLE 15 Preparation of 2-butylthio-6-benzylamino-9-β-D-ribofuranosylpurine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4e reacted with benzylamine for 8 hours; theresidue was separated by column chromatography (Et₃N-neutralized silicagel, gradient elution, MeOH-EtOAc, 1:50, 1:25, v/v) and recrystallizedwith EtOAc, the title compound was obtained as white crystals with ayield of 80%, m.p 170-172° C.; ¹H NMR (600 MHz, DMSO-d₆): δ 8.50 (1H, brs), 8.24 (1H, s), 7.28-7.31 (4H, m), 7.21 (1H, t, J=7.0 Hz), 5.81 (1H,d, J=5.9 Hz), 5.39 (1H, d, J=6.0 Hz), 5.14 (1H, d, J=4.8 Hz), 5.04 (1H,t, J=4.8 Hz), 4.67 (2H, br s), 4.59 (1H, ddd, J=5.5, 5.9, 6.1 Hz), 4.13(1H, ddd, J=4.3, 4.7, 5.5 Hz), 3.92 (1H, ddd, J=3.6, 4.6, 5.4 Hz),3.66-3.62 (1H, m), 3.55-3.51 (1H, m), 3.00 (2H, t, J=7.3 Hz), 1.59-1.54(2H, m), 1.35-1.31 (2H, m) 0.89 (3H, t, J=7.3 Hz).

EXAMPLE 16 Preparation of2-ethylthio-6-(1-phenylethyl)amino-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4b reacted with 1-phenylethylamine for 8 hours;the residue was separated by column chromatography (Et₃N-neutralizedsilica gel, gradient elution, MeOH-EtOAc, 1:30, 1:15, v/v) andrecrystallized with cyclohexane, the title compound was obtained aswhite crystals with a yield of 72%, m.p 84-86° C.; ¹H NMR (600 MHz,DMSO-d₆): δ 8.40 (1H, br s), 8.24 (1H, s), 7.40 (2H, d, J=7.1 Hz), 7.30(2H, t, J=7.5 Hz), 7.18 (1H, t, J=7.3 Hz), 5.80 (1H, d, J=5.9 Hz), 5.41(1H, m), 5.38 (1H, d, J=6.1 Hz), 5.13 (1H, d, J=4.8 Hz), 5.05 (1H, t,J=5.4 Hz), 4.58 (1H, ddd, J=5.7, 5.9, 6.1 Hz), 4.12 (1H, ddd, J=3.7,4.8, 5.7 Hz), 3.92 (1H, ddd, J=3.6, 4.2, 4.3 Hz), 3.64-3.62 (1H, m),3.54-3.51 (1H, m), 2.98 (2H, q, J=7.3 Hz), 1.53 (3H, d, J=6.8 Hz), 1.21(3H, t, J=7.3 Hz).

EXAMPLE 17 Preparation of2-propylthio-6-([4-methoxylbenzyl]amino)-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4c reacted with 4-methoxylbenzylamine for 11hours; the residue was separated by column chromatography(Et₃N-neutralized silica gel, gradient elution, MeOH-EtOAc, 1:30, 1:15,v/v) and recrystallized with EtOAc, the title compound was obtained aswhite crystals with a yield of 81%, m.p 152-154° C.; ¹H NMR (200 MHz,DMSO-d₆): δ 8.46 (1H, br s), 8.25 (1H, s), 7.26 (2H, d, J=8.6 Hz), 6.86(2H, d, J=8.6 Hz), 5.84 (1H, d, J=6.0 Hz), 5.47 (1H, d, J=6.0 Hz), 5.22(1H, d, J=4.8 Hz), 5.14 (1H, t, J=5.4 Hz), 4.61 (2H, br s), 4.58 (1H,ddd, J=5.8, 6.0, 6.1 Hz), 4.16 (1H, ddd, J=3.4, 4.8, 5.8 Hz), 3.95 (1H,ddd, J=3.4, 3.9, 4.6 Hz), 3.70 (3H, s), 3.64-3.61 (1H, m), 3.60-3.55(1H, m), 3.02 (2H, t, J=7.3 Hz), 1.54-1.72 (2H, m), 0.92 (3H, t, J=7.3Hz).

EXAMPLE 18 Preparation of2-methylthio-6-phenylethylamino-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4a reacted with 2-phenylethylamine for 9 hours;the residue was separated by column chromatography (Et₃N-neutralizedsilica gel, gradient elution, MeOH-EtOAc, 1:30, 1:15, v/v) andrecrystallized with EtOAc, the title compound was obtained as whitecrystals with a yield of 85%, m.p 156-158° C.; ¹H NMR (300 MHz,DMSO-d₆): δ 8.22 (1H, s), 8.02 (1H, br s), 7.30-7.25 (3H, m), 7.20-7.17(2H, m), 5.83 (1H, d, J=5.5 Hz), 5.45 (1H, d, J=5.5 Hz), 5.20 (1H, d,J=4.8 Hz), 5.08 (1H, t, J=5.4 Hz), 4.60 (1H, ddd, J=5.4, 5.5, 5.6 Hz),4.14 (1H, ddd, J=3.4, 4.2, 4.6 Hz), 3.92 (1H, ddd, J=3.4, 4.5, 4.9 Hz),3.68-3.65 (2H, m), 3.57-3.51 (2H, m), 2.90 (2H, t, J=7.6 Hz), 2.50 (3H,s).

EXAMPLE 19 Preparation of2-ethylthio-6-phenylethylamino-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4b reacted with 2-phenylethylamine for 9 hours;the residue was separated by column chromatography (Et₃N-neutralizedsilica gel, gradient elution, MeOH-EtOAc, 1:30, 1:15, v/v) andrecrystallized with EtOAc, the title compound was obtained as whitecrystals with a yield of 84%, m.p 130-132° C.; ¹H NMR (300 MHz,DMSO-d₆): δ 8.23 (1H, s), 8.02 (1H, br s), 7.32-7.26 (3H, m), 7.24-7.17(2H, m), 5.84 (1H, d, J=5.9 Hz), 5.45 (1H, d, J=6.2 Hz), 5.21 (1H, d,J=4.8 Hz), 5.11 (1H, t, J=5.5 Hz), 4.60 (1H, ddd, J=5.6, 5.7, 6.1 Hz),4.16 (1H, ddd, J=3.5, 4.8, 5.6 Hz), 3.95 (1H, ddd, J=3.5, 4.3, 4.8 Hz),3.67-3.65 (2H, m), 3.58-3.46 (2H, m), 3.11 (2H, q, J=7.3 Hz), 2.92 (2H,t, J=7.0 Hz), 1.34 (3H, t, J=7.3 Hz).

EXAMPLE 20 Preparation of2-propylthio-6-phenylethylamino-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4c reacted with 2-phenylethylamine for 9 hours;the residue was separated by column chromatography (Et₃N-neutralizedsilica gel, gradient elution, MeOH-EtOAc, 1:30, 1:15, v/v) andrecrystallized with EtOAc, the title compound was obtained as whitecrystals with a yield of 80%, m.p 110-112° C.; ¹H NMR (300 MHz,DMSO-d₆): δ 8.22 (1H, s), 8.03 (1H, br s), 7.32-7.26 (3H, m), 7.24-7.17(2H, m), 5.82 (1H, d, J=5.9 Hz), 5.44 (1H, d, J=6.2 Hz), 5.18 (1H, d,J=4.8 Hz), 5.10 (1H, t, J=5.4 Hz), 4.59 (1H, ddd, J=5.4, 5.9, 6.2 Hz),4.14 (1H, ddd, J=3.5, 4.2, 4.8 Hz), 3.93 (1H, ddd, J=3.5, 4.6, 5.2 Hz),3.69-3.64 (2H, m), 3.62-3.50 (2H, m), 3.09 (2H, t, J=7.3 Hz), 2.91 (2H,t, J=7.0 Hz), 1.74-1.67 (2H, m), 0.97 (3H, t, J=7.3 Hz).

EXAMPLE 21 Preparation of2-butylthio-6-phenylethylamino-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4e reacted with 2-phenylethylamine for 9 hours;the residue was separated by column chromatography (Et₃N-neutralizedsilica gel, gradient elution, MeOH-EtOAc, 1:30, 1:15, v/v) andrecrystallized with EtOAc, the title compound was obtained as whitecrystals with a yield of 81%, m.p 124-126° C.; ¹H NMR (400 MHz,DMSO-d₆): δ 8.20 (1H, s), 8.01 (1H, br s), 7.31-7.26 (3H, m), 7.25-7.18(2H, m), 5.80 (1H, d, J=5.6 Hz), 5.41 (1H, d, J=6.1 Hz), 5.16 (1H, d,J=4.8 Hz), 5.07 (1H, t, J=5.4 Hz), 4.57 (1H, ddd, J=5.6, 5.7, 6.1 Hz),4.12 (1H, ddd, J=3.7, 4.7, 5.7 Hz), 3.92 (1H, ddd, J=3.7, 4.6, 5.8 Hz),3.68-3.64 (2H, m), 3.62-3.50 (2H, m), 3.10 (2H, t, J=7.3 Hz), 2.91 (2H,t, J=7.5 Hz), 1.70-1.63 (2H, m), 1.45-1.36 (2H, m), 0.89 (3H, t, J=7.3Hz).

EXAMPLE 22 Preparation of2-methylthio-6-([4-methoxylphenylethyl]-amino)-9-β-D-ribofuranosylpurine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4a reacted with 4-methoxylphenylethylamine for 12hours; the residue was separated by column chromatography(Et₃N-neutralized silica gel, gradient elution, MeOH-EtOAc, 1:30, 1:15,v/v) and recrystallized with EtOAc, the title compound was obtained aswhite crystals with a yield of 82%, m.p 152-154° C.; ¹H NMR (300 MHz,DMSO-d₆): δ 8.24 (1H, s), 7.97 (1H, br s), 7.16 (2H, d, J=7.9 Hz), 6.85(2H, d, J=8.0 Hz), 5.87 (1H, d, J=5.9 Hz), 5.47 (1H, d, J=5.9 Hz), 5.24(1H, d, J=4.8 Hz), 5.12 (1H, t, J=5.4 Hz), 4.63 (1H, ddd, J=5.4, 5.8,6.2 Hz), 4.19 (1H, ddd, J=3.5, 4.8, 5.4 Hz), 3.97 (1H, ddd, J=3.5, 4.3,4.6 Hz), 3.70 (3H, s), 3.65-3.66 (2H, m), 3.53-3.49 (2H, m), 2.85 (2H,t, J=7.1 Hz), 2.52 (3H, s).

EXAMPLE 23 Preparation of2-ethylthio-6-([4-methoxylphenylethyl]amino)-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4b reacted with 4-methoxylphenylethylamine for 9hours; the residue was separated by column chromatography(Et₃N-neutralized silica gel, gradient elution, MeOH-EtOAc, 1:30, 1:15,v/v) and recrystallized with EtOAc, the title compound was obtained aswhite crystals with a yield of 81%, m.p 140-142° C.; ¹H NMR (200 MHz,DMSO-d₆): δ 8.25 (1H, s), 7.99 (1H, br s), 7.16 (2H, d, J=8.0 Hz), 6.85(2H, d, J=8.0 Hz), 5.86 (1H, d, J=5.9 Hz), 5.47 (1H, d, J=5.9 Hz), 5.22(1H, d, J=4.8 Hz), 5.13 (1H, t, J=5.4 Hz), 4.63 (1H, ddd, J=5.4, 5.9,6.2 Hz), 4.17 (1H, ddd, J=3.4, 4.8, 5.4 Hz), 3.98 (1H, ddd, J=3.4, 4.2,4.6 Hz), 3.70 (3H, s), 3.66-3.60 (2H, m), 3.54-3.44 (2H, m), 3.12 (2H,q, J=7.3 Hz), 2.85 (2H, t, J=7.1 Hz), 1.35 (3H, t, J=7.3 Hz).

EXAMPLE 24 Preparation of2-propylthio-6-([4-methoxylphenylethyl]amino)-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4c reacted with 4-methoxylphenylethylamine for 12hours; the residue was separated by column chromatography(Et₃N-neutralized silica gel, gradient elution, MeOH-EtOAc, 1:30, 1:15,v/v) and recrystallized with EtOAc, the title compound was obtained aswhite crystals with a yield of 83%, m.p 170-172° C.; ¹H NMR (300 MHz,DMSO-d₆): δ 8.21 (1H, s), 8.00 (1H, br s), 7.15 (2H, d, J=8.0 Hz), 6.85(2H, d, J=8.0 Hz), 5.81 (1H, d, J=5.9 Hz), 5.42 (1H, d, J=5.9 Hz), 5.17(1H, d, J=4.8 Hz), 5.08 (1H, t, J=5.4 Hz), 4.59 (1H, ddd, J=5.3, 5.8,5.8 Hz), 4.13 (1H, br s), 3.92 (1H, ddd, J=3.5, 4.6, 5.6 Hz), 3.71 (3H,s), 3.64-3.62 (2H, m), 3.55-3.51 (2H, m), 3.09 (2H, t, J=7.3 Hz), 2.84(2H, t, J=7.5 Hz), 1.74-1.64 (2H, m), 0.98 (3H, t, J=7.3 Hz).

EXAMPLE 25 Preparation of2-butylthio-6-([4-methoxylphenylethyl]amino)-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4e reacted with 4-methoxylphenylethylamine for 12hours; the residue was separated by column chromatography(Et₃N-neutralized silica gel, gradient elution, MeOH-EtOAc, 1:30, 1:15,v/v) and recrystallized with EtOAc, the title compound was obtained aswhite crystals with a yield of 80%, m.p 122-124° C.; ¹H NMR (400 MHz,DMSO-d₆): δ 8.21 (1H, s), 7.98 (1H, br s), 7.15 (2H, d, J=8.0 Hz), 6.85(2H, d, J=8.2 Hz), 5.80 (1H, d, J=5.8 Hz), 5.41 (1H, d, J=5.9 Hz), 5.16(1H, d, J=4.8 Hz), 5.07 (1H, t, J=4.9 Hz), 4.58 (1H, ddd, J=5.2, 5.8,6.1 Hz), 4.13 (1H, ddd, J=3.8, 4.8, 5.2 Hz), 3.92 (1H, ddd, J=3.8, 4.3,4.6 Hz), 3.71 (3H, s), 3.67-3.64 (2H, m), 3.53-3.518 (2H, m), 3.10 (2H,t, J=7.3 Hz), 2.84 (2H, t, J=7.1 Hz), 1.70-1.63 (2H, m), 1.46-1.37 (2H,m), 0.89 (3H, t, J=7.3 Hz).

EXAMPLE 26 Preparation of2-ethylthio-6-([3-methoxylphenylethyl]amino)-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4b reacted with 3-methoxylphenylethylamine for 11hours; the residue was separated by column chromatography(Et₃N-neutralized silica gel, gradient elution, MeOH-EtOAc, 1:30, 1:15,v/v) and recrystallized with EtOAc, the title compound was obtained aswhite crystals with a yield of 84%, m.p 110-112° C.; ¹H NMR (300 MHz,DMSO-d₆): δ 8.22 (1H, s), 8.01 (1H, br s), 7.20 (1H, t, J=8.0 Hz),6.81-6.75 (3H, m), 5.82 (1H, d, J=5.9 Hz), 5.43 (1H, d, J=6.1 Hz), 5.18(1H, d, J=4.8 Hz), 5.08 (1H, t, J=5.4 Hz), 4.59 (1H, ddd, J=5.4, 5.7,6.1 Hz), 4.14 (1H, ddd, J=3.7, 4.8, 5.4 Hz), 3.93 (1H, ddd, J=3.7, 4.5,4.6 Hz), 3.72 (3H, s), 3.70-3.63 (2H, m), 3.58-3.53 (2H, m), 3.11 (2H,q, J=7.3 Hz), 2.89 (2H, t, J=7.6 Hz), 1.34 (3H, t, J=7.3 Hz).

EXAMPLE 27 Preparation of2-propylthio-6-([3-methoxylphenylethyl]amino)-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4c reacted with 3-methoxylphenylethylamine for 11hours; the residue was separated by column chromatography(Et₃N-neutralized silica gel, gradient elution, MeOH-EtOAc, 1:30, 1:15,v/v) and recrystallized with EtOAc, the title compound was obtained aswhite crystals with a yield of 76%, imp 120-122° C.; ¹H NMR (300 MHz,DMSO-d₆) δ 8.22 (1H, s), 8.01 (1H, br s), 7.20 (1H, t, J=8.0 Hz),6.82-6.75 (3H, m), 5.81 (1H, d, J=6.0 Hz), 5.43 (1H, d, J=6.1 Hz), 5.18(1H, d, J=4.8 Hz), 5.09 (1H, t, J=5.5 Hz, 4.60 (1H, ddd, J=5.7, 5.9, 6.1Hz), 4.13 (1H, ddd, J=3.4, 4.8, 5.7 Hz), 3.92 (1H, ddd, J=3.3, 4.0, 4.5Hz), 3.72 (3H, s), 3.67-3.62 (2H, m), 3.57-3.50 (2H, m), 3.09 (2H, t,J=7.3 Hz), 2.89 (2H, t, J=7.1 Hz), 1.74-1.64 (2H, m), 0.98 (3H, t, J=7.3Hz).

EXAMPLE 28 Preparation of2-ethylthio-6,6-(dibutylamino)-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4b reacted with n-dibutylamine for 14 hours; theresidue was separated by column chromatography (Et₃N-neutralized silicagel, gradient elution, EtOAc-petroleum ether, 1:10, 1:1, v/v) andrecrystallized with n-hexane, the title compound was obtained as whitecrystals with a yield of 58%, m.p 152-154° C.; ¹H NMR(400 MHz, DMSO-d₆):δ 8.24 (1H, s), 5.82 (1H, d, J=6.0 Hz), 5.41 (1H, d, J=6.2 Hz), 5.17(1H, d, J=4.8 Hz), 5.07 (1H, t, J=5.2 Hz), 4.55 (1H, ddd, J=5.3, 6.0,6.2 Hz), 4.12 (1H, ddd, J=3.4, 4.9, 5.3 Hz), 3.92 (1H, ddd, J=3.4, 4.6,6.2 Hz), 3.67-3.62 (2H, m), 3.62-3.49 (4H, m), 3.12-3.04 (2H, m),1.66-1.56 (4H, m), 1.39-1.34 (4H, m), 1.32 (3H, t, J=7.3 Hz), 0.92 (6H,t, J=6.4 Hz).

EXAMPLE 29 Preparation of2-ethylthio-6-(2-thienylethyl)amino-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4b reacted with 2-thienylethylamine for 4 hours;the residue was separated by column chromatography (Et₃N-neutralizedsilica gel, MeOH-EtOAc, 1:20, v/v) and recrystallized with EtOAc, thetitle compound was obtained as white crystals with a yield of 80%, m.p142-144° C.; ¹H NMR (400 MHz, DMSO-d₆): δ 8.23 (1H, s), 8.09 (1H, br s),7.32 (1H, dd, J=1.08, 1.12 Hz,), 6.96-6.91 (2H, m), 5.81(1H, d, J=5.92Hz), 5.42 (1H, d, J=6.08 Hz), 5.17 (1H, d, J=4.56 Hz), 5.07 (1H, t,J=6.09 Hz), 4.58 (1H, q, J=5.63, 5.75 Hz) 4.12 (1H, q, J=4.71, 4.50 Hz),3.91 (1H, q, J=3.79, 3.79 Hz), 3.71-3.63 (3H, m), 3.56-3.50 (1H, m),3.15-3.07 (4H, m), 1.33 (3H, t, J=7.24 Hz).

EXAMPLE 30 Preparation of2-propylthio-6-(2-thienylethyl)amino-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4c reacted with 2-thienylethylamine for 5 hours;the residue was separated by column chromatography (Et₃N-neutralizedsilica gel, MeOH-EtOAc, 1:15, v/v) and recrystallized with n-hexane, thetitle compound was obtained as white crystals with a yield of 70%, ¹HNMR (400 MHz, DMSO-d₆): δ 8.22 (1H, s), 8.09 (1H, br s), 7.32 (1H, dd,J=1.11, 1.11 Hz), 6.96-6.91 (2H, m), 5.80 (1H, d, J=5.92 Hz), 5.41 (1H,d, J=5.96 Hz), 5.17 (1H, d, J=3.89 Hz), 5.07 (1H, t, J=6.22 Hz),4.58(1H, q, J=5.63, 5.75 Hz), 4.12 (1H, m), 3.91 (1H, q, J=3.69, 3.69Hz,), 3.71-3.62 (3H, m), 3.55-3.51 (1H, m), 3.15-3.076 (4H, m), 1.69(2H, sextet, J=7.29), 0.97 (3H, t, J=7.29 Hz).

EXAMPLE 31 Preparation of2-ethylthio-6-(3-phenylpropyl)amino-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4b reacted with 3-phenyl-1-propylamine for 4hours; the residue was separated by column chromatography(Et₃N-neutralized silica gel, MeOH-EtOAc, 1:20, v/v) and recrystallizedwith methanol, the title compound was obtained as white crystals with ayield of 80%, m.p 180-182° C.; ¹H NMR (400 MHz, DMSO-d₆): δ 8.22 (1H,s), 8.03 (1H, br s), 7.29-7.15(5H, m), 5.81 (1H, d, J=5.98 Hz), 5.41(1H, d, J=6.09 Hz), 5.17 (1H, d, J=4.83 Hz), 5.07 (1H, t, J=5.05 Hz),4.58 (1H, q, J=5.86, 5.97 Hz), 4.12 (1H, q, J=4.60, 4.71 Hz), 3.91 (1H,q, J=3.91, 3.79 Hz), 3.66-3.61 (1H, m), 3.55-3.46 (3H, m), 3.02 (2H, q,J=7.91, 7.36 Hz), 2.63 (2H, t, J=7.47 Hz), 1.89 (2H, q, J=7.47 Hz), 1.29(3H, t, J=7.24 Hz).

EXAMPLE 32 Preparation of2-ethylthio-6-(4-phenylbutyl)amino-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4b reacted with 4-phenyl-1-butylamine for 5 hours;the residue was separated by column chromatography (Et₃N-neutralizedsilica gel, MeOH-EtOAc, 1:20, v/v) and recrystallized with methanol, thetitle compound was obtained as white crystals with a yield of 80%, m.p146-148° C.; ¹H NMR (400 MHz, DMSO-d₆): δ 8.20 (1H, s), 7.98 (1H, br s),7.28-7.14 (5H, m), 5.81 (1H, d, J=5.85 Hz), 5.42 (1H, d, J=6.06 Hz),5.18 (1H, d, J=4.70 Hz), 5.08 (1H, t, J=5.17 Hz), 4.59 (1H, q, J=5.69Hz, 5.85 Hz), 4.12 (1H, q, J=4.49, 4.60 Hz), 3.91 (1H, q, J=3.97, 3.86Hz), 3.67-3.61 (1H, m), 3.56-3.47 (m, 3H), 3.05 (2H, dd, J=2.03, 1.88Hz), 2.60 (2H, t, J=7.05 Hz), 1.89 (2H, q, J=7.47 Hz), 1.61 (4H, br),1.31 (3H, t, J=7.24 Hz).

EXAMPLE 33 Preparation of2-ethylthio-6-(2-furylmethyl)amino-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4b reacted with 2-furylmethylamine for 5 hours;the residue was separated by column chromatography (Et₃N-neutralizedsilica gel, MeOH-EtOAc, 1:15, v/v) and recrystallized with a mixedsolvent of ethyl acetate and petroleum ether, the title compound wasobtained as white crystals with a yield of 75%, m.p 190-192° C.; ¹H NMR(400 MHz, DMSO-d₆): δ 8.41 (1H, br s), 8.26 (1H, s), 7.55 (1H, s), 6.37(1H, m), 6.22 (1H, m), 5.82 (1H, d, J=5.92 Hz), 5.43 (1H, d, J=6.07 Hz),5.17 (1H, d, J=4.80 Hz), 5.05 (1H, t, J=5.50 Hz), 4.65-4.57 (3H, m),4.12 (1H, q, J=4.51, 4.66 Hz), 3.92 (1H, q, J=3.67, 3.67 Hz), 3.67-3.62(1H, m), 3.56-3.50 (1H, m), 3.07 (2H, dd, J=2.11, 1.97 Hz), 1.30 (3H, t,J=7.19 Hz).

EXAMPLE 34 Preparation of2-ethylthio-6-(2-tetrahydrofurylmethyl)amino-9-β-D-ribofuranosyl purine

The preparation method above-mentioned in Example 8 was used, exceptthat the intermediate 4b reacted with 2-tetrahydrofurylmethylamine for 5hours; the residue was separated by column chromatography(Et₃N-neutralized silica gel, MeOH-EtOAc, 1:15, v/v) and recrystallizedwith methanol, the title compound was obtained as white crystals with ayield of 82%, m.p 89-91° C.; ¹H NMR (400 MHz, DMSO-d₆): δ 8.23 (1H, s),7.85 (1H, br s), 5.81 (1H, d, J=5.93 Hz), 5.42 (1H, d, J=6.21 Hz), 5.17(1H, d, J=4.80 Hz), 5.06 (1H, t, J=5.36 Hz), 4.58 (1H, q, J=5.78, 5.78Hz), 4.13 (1H, q, J=4.65, 4.93 Hz), 4.09 (1H, m), 3.92 (1H, q, J=3.81,3.81 Hz), 3.77 (1H, q, J=7.05, 6.35 Hz), 3.67-3.59 (2H, m), 3.56-3.50(2H, m), 3.45 (1H, t, J=5.93 Hz), 3.09-3.05 (2H, m), 1.93-1.74 (3H, m),1.67-1.61 (1H, m), 1.33 (3H, t, J=7.34 Hz).

II. Preparation Examples of Formulations FORMULATION EXAMPLE 1Preparation of Injection

40.0 g of a compound of Example 19 was sufficiently mixed with 22.56 gof disodium hydrogen phosphate, 0.519 g of sodium dihydrogen phosphate,2 g of sodium metabisulfite, 5 g of benzyl alcohol, 5 g of glycerol.Water for injection was added to 1000 mL, to obtain the injectioncontaining the compound of the present invention.

FORMULATION EXAMPLE 2 Preparation of Tablets

5 g of a compound of Example 18, 12 g of lactose, 8 g of corn starch,0.2 g of magnesium stearate and 0.02 g of methyl cellulose were mixedtogether and compressed according to the conventional methods to obtain100 tablets.

III. Bioactivity Assay

The inventor conducted the anti-platelet aggregation activity screeningfor the compounds of the present invention, carried out theanti-platelet aggregation test by using the blood platelet which wasclosed to human physiological state and was not washed with water, andconducted the activity test of the in vitro anti-platelet aggregationinduced by ADP, and also the activity test of the in vitro anti-plateletaggregation induced by AA (arachidonic acid) for some compounds. Thepresent invention firstly discloses the activity test of the in vitroanti-platelet aggregation induced by AA conducted with said type ofcompounds. The results show that the compounds of the present inventionhave a notable anti-platelet aggregation activity.

Evaluation of Anti-Platelet Aggregation Activity

The anti-platelet aggregation test of the compounds was conducted by theaggregometer (Model 400VS, Chrono-Log, Haverston, Pa.) from Chrono-LogCorp. ADP, AA (arachidonic acid), DMSO and trisodium citrate werepurchased from Sigama.

1. Test Method:

The whole blood was obtained from healthy volunteers who did not takeany anti-platelet medicines within 2 weeks. The fasting venous blood ofthe subjects was collected, and placed into a 50 mL sampling tubecontaining 3.8% sodium citrate, and mixed homogeneously in a ratio of1:9 (v/v) for anticoagulation, and centrifugalized at 300 rpm/min for 20min.

The supernatant was taken to obtain platelet-rich blood plasma (PRP).The residual blood was then centrifugalized at 900 rpm/min for 10 min,and the supernatant fluid was taken to obtain platelet-poverty bloodplasma (PPP). The analysis of platelet aggregation was conducted byusing the aggregometer (Chrono-Log Corp.), wherein PRP and PPP wererespectively added to two turbidimetric tubes. In the aggregometer,platelet-poverty blood plasma (PPP) was used as the control group. DMSOwas used as the negative control. The turbidimetric tubes were incubatedat 37° C. for 3 min. The PRP was stirred with a stirring rod at 900rpm/min for 10-20 s, and the inductive agent ADP (10 uM) or AA (0.5 mM)was added to PRP, and start to record the aggregated wave patterns. Thechart speed of the recorder (Model 707, Chrono-Log, Haverston, Pa., USA)was set up to be 1 cm min⁻¹, and the aggregation reaction was recordedfor not less than 3 min. Finally, the apparatus automatically delineatedthe aggregation curve and calculated the results, i.e. maximum plateletaggregation rate. When the platelet aggregation was lower than 50% ofthe control group, the IC₅₀ of the compound was calculated.

2. Test Results: See Table 1

TABLE 1 Activities of the in vitro anti-platelet aggregation of thecompounds of the present invention Compounds IC₅₀ (ADP, μM) IC₅₀ (AA,μM) Example 8 102 Example 9 104 Example 10 151 Example 11 187 Example 1283 Example 13 176 Example 14 216 Example 15 202 Example 16 197 Example17 181 Example 18 36 3 Example 19 29 30 Example 20 52 44 Example 2159 >300 Example 22 153 Example 23 89 Example 24 267 Example 25 93Example 26 38 >300 Example 27 69

The results of the in vitro anti-platelet aggregation tests have showedthat all the compounds have the effect of in vitro inhibitingADP-induced platelet aggregation in various extents; and at the sametime, a part of the compounds have a notable effect on in vitroinhibiting AA (arachidonic acid)-induced platelet aggregation.

1. A compound represented by the formula (I-1) or a pharmaceuticallyacceptable salt thereof

wherein R₁ represents an unsubstituted or R₄-substituted C₁-C₈hydrocarbyl, or an unsubstituted or R₅-substituted 5- to 6-memberedcyclic group; R_(2a) represents an unsubstituted or R₅-substituted C₃-C₈saturated or unsaturated aliphatic hydrocarbyl, an unsubstituted orR₅-substituted C₃-C₈ alicyclic group, an unsubstituted or R₆-substitutedC₆-C₁₀ aryl-C₂-C₄ alkyl, an unsubstituted or R₆-substituted 5- to10-membered heterocyclyl-C₁-C₄ alkyl, or an unsubstituted orR₆-substituted 5- to 10-membered heteroaryl-C₁-C₄ alkyl; R₃ represents Hor R_(2a); R₄ represents halogen, C₁-C₄ alkyl, C₁-C₄ alkoxyl,halogenated C₁-C₄ alkyl, halogenated C₁-C₄ alkoxyl, hydroxyl, hydroxylC₁-C₄ alkyl, carboxyl, nitro, cyano, C₁-C₄ alkylthio, or C₁-C₄alkyl-CO—; R₅ represents C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl, hydroxylC₁-C₄ alkyl, carboxyl, nitro, cyano, C₁-C₄ alkylthio or C₁-C₄ alkyl-CO—;and R₆ represents halogen, C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl,hydroxyl C₁-C₄ alkyl, carboxyl, nitro, cyano, C₁-C₄ alkylthio, or C₁-C₄alkyl-CO—; provided that when R₁ is —CH₃ and R₃ is H, R_(2a) is notcyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, decalinyl,3-methyl-2-pentenyl, 2-methyl-3-hydroxyl-1-propenyl,3-methyl-4-hydroxyl-1-butenyl, furfurylmethylene, 3-methyl-1-butenyl,3-methyl-2-butenyl, 3-methylbutyl, 3-methyl-4-hydroxylbutyl,3-methyl-4-hydroxyl-2-butenyl or 3-methyl-4-hydroxyl-3-butenyl; or whenR₁ is propyl, R_(2a) is not cyclopentyl, isopropyl, n-propyl or n-butyl.2. The compound according to claim 1 or a pharmaceutically acceptablesalt thereof, wherein R₁ represents an unsubstituted or R₄-substitutedC₁-C₆ alkyl, wherein R₄ represents halogen, C₁-C₄ alkyl, C₁-C₄ alkoxyl,halogenated C₁-C₄ alkyl, halogenated C₁-C₄ alkoxyl, hydroxyl, hydroxylC₁-C₄ alkyl, carboxyl, nitro, cyano, C₁-C₄ alkylthio, or C₁-C₄alkyl-CO—.
 3. The compound according to claim 1 or a pharmaceuticallyacceptable salt thereof, wherein R_(2a) represents an unsubstituted orR₅-substituted C₃-C₆ alkyl, an unsubstituted or R₅-substituted C₃-C₆cycloalkyl, an unsubstituted or R₆-substituted 5- to 6-memberedheteroaryl-C₁-C₄ alkyl, an unsubstituted or R₆-substituted phenyl-C₂-C₄alkyl, or an unsubstituted or R₆-substituted 5- to 6-memberedheterocyclyl-C₁-C₄ alkyl, wherein R₅ is selected from the groupconsisting of C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl, hydroxyl C₁-C₄alkyl, carboxyl, nitro, cyano, C₁-C₄ alkylthio and C₁-C₄ alkyl-CO—; andR₆ is selected from the group consisting of halogen, C₁-C₄ alkyl, C₁-C₄alkoxyl, hydroxyl, hydroxyl C₁-C₄ alkyl, carboxyl, nitro, cyano, C₁-C₄alkylthio, and C₁-C₄ alkyl-CO—.
 4. The compound according to claim 1 ora pharmaceutically acceptable salt thereof, wherein R₁ represents C₁-C₆alkyl; R_(2a) represents C₃-C₆ alkyl, C₃-C₆ cycloalkyl, an unsubstitutedor R₆-substituted phenyl-C₂-C₄ alkyl, an unsubstituted or R₆-substituted5- to 6-membered heteroaryl-C₁-C₄ alkyl, or an unsubstituted orR₆-substituted 5- to 6-membered heterocyclyl-C₁-C₄ alkyl, wherein R₆ isselected from the group consisting of halogen, C₁-C₄ alkyl, C₁-C₄alkoxyl, hydroxyl, hydroxyl C₁-C₄ alkyl, carboxyl, nitro, cyano, C₁-C₄alkylthio and C₁-C₄ alkyl-CO—.
 5. The compound according to claim 1 or apharmaceutically acceptable salt thereof, wherein R₁ represents C₁-C₄alkyl; R_(2a) represents C₃-C₆ alkyl, C₅-C₆ cycloalkyl, unsubstituted orC₁-C₄ alkyl-substituted or C₁-C₄ alkoxyl-substituted phenyl-C₂-C₄ alkyl,unsubstituted or C₁-C₄ alkyl-substituted or C₁-C₄ alkoxyl-substituted 5-to 6-membered heteroaryl-C₁-C₄ alkyl, or unsubstituted or C₁-C₄alkyl-substituted or C₁-C₄ alkoxyl-substituted 5- to 6-memberedheterocyclyl-C₁-C₄ alkyl.
 6. The compound according to claim 1 or apharmaceutically acceptable salt thereof, wherein R₁ represents methyl,ethyl, n-propyl, isopropyl or butyl; R_(2a) represents n-hexyl,cyclohexyl, 2-phenylethyl, 3-phenylpropyl, 4-phenylbutyl,methoxylphenylethyl, 2-thienylethyl, furylmethyl, ortetrahydrofurylmethyl.
 7. The compound according to claim 1 or apharmaceutically acceptable salt thereof, wherein R₃ represents H orC₃-C₆ alkyl.
 8. The following compounds or pharmaceutically acceptablesalts thereof: 2-propylthio-6-n-hexylamino-9-β-D-ribofuranosyl purine;2-ethylthio-6-cyclohexylamino-9-β-D-ribofuranosyl purine;2-propylthio-6-cyclohexylamino-9-β-D-ribofuranosyl purine;2-isopropylthio-6-cyclohexylamino-9-β-D-ribofuranosyl purine;2-butylthio-6-cyclohexylamino-9-β-D-ribofuranosyl purine;2-ethylthio-6-benzylamino-9-β-D-ribofuranosyl purine;2-propylthio-6-benzylamino-9-β-D-ribofuranosyl purine;2-butylthio-6-benzylamino-9-β-D-ribofuranosyl purine;2-ethylthio-6-(1-phenylethyl)amino-9-β-D-ribofuranosyl purine;2-propylthio-6-([4-methoxylbenzyl]amino)-9-β-D-ribofuranosyl purine;2-methylthio-6-phenylethylamino-9-β-D-ribofuranosyl purine;2-ethylthio-6-phenylethylamino-9-β-D-ribofuranosyl purine;2-propylthio-6-phenylethylamino-9-β-D-ribofuranosyl purine;2-butylthio-6-phenylethylamino-9-β-D-ribofuranosyl purine;2-methylthio-6-([4-methoxylphenylethyl]amino)-9-β-D-ribofuranosylpurine; 2-ethylthio-6-([4-methoxylphenylethyl]amino)-9-β-D-ribofuranosylpurine;2-propylthio-6-([4-methoxylphenylethyl]amino)-9-β-D-ribofuranosylpurine; 2-butylthio-6-([4-methoxylphenylethyl]amino)-9-β-D-ribofuranosylpurine; 2-ethylthio-6-([3-methoxylphenylethyl]amino)-9-β-D-ribofuranosylpurine;2-propylthio-6-([3-methoxylphenylethyl]amino)-9-β-D-ribofuranosylpurine; 2-ethylthio-6,6-(dibutylamino)-9-β-D-ribofuranosyl purine;2-propylthio-6-(2-thienylethyl)amino-9-β-D-ribofuranosyl purine;2-ethylthio-6-(3-phenylpropyl)amino-9-β-D-ribofuranosyl purine;2-ethylthio-6-(4-phenylbutyl)amino-9-β-D-ribofuranosyl purine;2-ethylthio-6-(2-furylmethyl)amino-9-β-D-ribofuranosyl purine; and2-ethylthio-6-(2-tetrahydrofurylmethyl)amino-9-β-D-ribofuranosyl purine.9. A process for preparing the compound according to claim 1,

wherein R is acyl; R₁, R_(2a) and R₃ are as defined in claim 1; whichcomprises: using guanosine 1 as the starting material, firstlyconducting the conventional esterification protection of three hydroxylgroups on the ribose ring of guanosine with an acid anhydride or an acylhalide, then halogenating the isomerized hydroxyl group at 6-positionusing the conventional halogenating reagent to obtain2-amino-6-halogenated-9-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosyl)purine3, then under an anhydrous condition diazotizing the amino at 2-positionof 3 with a conventional diazotization reagent, and then reacting withdisulfide to obtain the corresponding2-alkylthio-6-halogenated-9-(2′,3′,5′-tri-O-acetyl-(3-D-ribofuranosyl)purine4, eventually conducting the nucleophilic substitution reaction withamine under the action of an alkaline, and removing the protecting groupby the catalysis of alkali metal alkoxides to obtain the final productcompound of the formula (I-1).
 10. A pharmaceutical composition,comprising the compound according to claim 1 or a pharmaceuticallyacceptable salt thereof.
 11. A pharmaceutical formulation, comprisingthe compound according to claim 1 or a pharmaceutically acceptable saltthereof and a pharmaceutically acceptable carrier.
 12. A method for thetreatment or prevention of diseases associated with platelet aggregationin a mammal in need thereof, comprising administering an effectiveamount of the compound of the formula (I) or a pharmaceuticallyacceptable salt thereof,

wherein R₁ represents an unsubstituted or R₄-substituted C₁-C₈hydrocarbyl, or an unsubstituted or R₅-substituted 5- to 6-memberedcyclic group; R₂ represents an unsubstituted or R₅-substituted C₃-C₈saturated or unsaturated aliphatic hydrocarbyl, an unsubstituted orR₅-substituted C₃-C₈ alicyclic group, an unsubstituted or R₆-substitutedC₆-C₁₀ aryl-C₁-C₄ alkyl, an unsubstituted or R₆-substituted 5- to10-membered heterocyclyl-C₁-C₄ alkyl, or an unsubstituted orR₆-substituted 5- to 10-membered heteroaryl-C₁-C₄ alkyl; R₃ represents Hor R₂; R₄ represents halogen, C₁-C₄ alkyl, C₁-C₄ alkoxyl, halogenatedC₁-C₄ alkyl, halogenated C₁-C₄ alkoxyl, hydroxyl, hydroxyl C₁-C₄ alkyl,carboxyl, nitro, cyano, C₁-C₄ alkylthio, or C₁-C₄ alkyl-CO—; R₅represents C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl, hydroxyl C₁-C₄ alkyl,carboxyl, nitro, cyano, C₁-C₄ alkylthio or C₁-C₄ alkyl-CO—; and R₆represents halogen, C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl, hydroxyl C₁-C₄alkyl, carboxyl, nitro, cyano, C₁-C₄ alkylthio, or C₁-C₄ alkyl-CO—. 13.The method according to claim 12, wherein R₁ represents an unsubstitutedor R₄-substituted C₁-C₆ alky; R₂ represents an unsubstituted orR₅-substituted C₃-C₆ alkyl, an unsubstituted or R₅-substituted C₃-C₆cycloalkyl, an unsubstituted or R₆-substituted 5- to 6-memberedheteroaryl-C₁-C₄ alkyl, an unsubstituted or R₆-substituted phenyl-C₁-C₄alkyl, or an unsubstituted or R₆-substituted 5- to 6-memberedheterocyclyl-C₁-C₄ alkyl; and R₃ represents H or C₃-C₆ alkyl; wherein R₄represents halogen, C₁-C₄ alkyl, C₁-C₄ alkoxyl, halogenated C₁-C₄ alkyl,halogenated C₁-C₄ alkoxyl, or C₁-C₄ alkylthio; R₅ is selected from thegroup consisting of C₁-C₄ alkyl, C₁-C₄ alkoxyl, hydroxyl, hydroxyl C₁-C₄alkyl, carboxyl, nitro, cyano, C₁-C₄ alkylthio or C₁-C₄ alkyl-CO—; andR₆ is selected from the group consisting of halogen, C₁-C₄ alkyl, C₁-C₄alkoxyl, hydroxyl, hydroxyl C₁-C₄ alkyl, carboxyl, nitro, cyano, C₁-C₄alkylthio, and C₁-C₄ alkyl-CO—.
 14. The method according to claim 13,wherein R₁ represents C₁-C₆ alkyl; R₂ represents C₃-C₆ alkyl, C₅-C₆cycloalkyl, an unsubstituted or R₆-substituted phenyl-C₁-C₄ alkyl, anunsubstituted or R₆-substituted 5- to 6-membered heteroaryl-C₁-C₄ alkyl,or an unsubstituted or R₆-substituted 5- to 6-memberedheterocyclyl-C₁-C₄ alkyl, wherein R₆ is selected from the groupconsisting of C₁-C₄ alkyl, C₁-C₄ alkoxyl and C₁-C₄ alkylthio.
 15. Themethod according to claim 13, wherein R₁ represents methyl, ethyl,n-propyl, isopropyl or butyl; R₂ represents n-hexyl, cyclohexyl,1-phenylethyl, 2-phenylethyl, 3-phenylpropyl, 4-phenylbutyl,methoxylphenylethyl, 2-thienylethyl, furylmethyl, ortetrahydrofurylmethyl.
 16. The method use according to claim 12, whereinthe disease associated with platelet aggregation is selected from thegroup consisting of thrombotic diseases, viral diseases having ahypercoagulable state, neoplastic diseases, coronary heart disease,stroke, hypertension, leukemia and disseminated intravascularcoagulation (DIC).